Thermally insulative smoking article filter components

Abstract

A filter component includes a catalyst surrounded by a thermally insulative carbon fiber composite. The catalyst can catalyze the chemical reaction of selected gaseous constituents of a gas stream. During catalysis, the catalyst can reach high temperatures. The carbon fiber composite can contain heat generated during the catalysis within the filter component and thereby reduce heat transfer to the surroundings. The filter component can be used in smoking articles. Methods of making and using the filter-component and methods for treating mainstream tobacco smoke are also provided.

1. A cigarette filter, comprising:
 a filter component including: 
 a thermally insulative porous, carbon-bonded carbon fiber composite, wherein the carbon fiber composite is tubular and comprises an inner surface defining a cavity; and 
 a catalyst contained within the cavity, the catalyst being effective to catalyze the chemical reaction of at least one selected constituent of mainstream tobacco smoke in the cigarette filter, 
 wherein the catalyst substantially fills the cavity. 
 
     
     
       2. The cigarette filter of  claim 1 , wherein the carbon fiber composite comprises carbon fibers interbonded by a carbonized material. 
     
     
       3. The cigarette filter of  claim 1 , wherein the carbon fiber composite has a density of from about 0.2 g/cm 3  to about 0.6 g/cm 3  and a thermal conductivity of from about 0.1 W/mK to about 0.3 W/mK. 
     
     
       4. The cigarette filter of  claim 1 , wherein the carbon fiber composite comprises carbon fibers selected from the group consisting of rayon fibers, pitch fibers and poly(acrylonitrile) fibers. 
     
     
       5. The cigarette filter of  claim 1 , wherein the catalyst is effective to catalyze at least the oxidation of CO. 
     
     
       6. The cigarette filter of  claim 1 , wherein the catalyst is a mixed metal cobalt-based oxide catalyst comprising an oxide of cobalt and an oxide of one or more of Al, Bi, Ce, Cr, Cu, Fe, La, Mg, Mn, Ti, Zn and Zr. 
     
     
       7. The cigarette filter of  claim 1 , wherein the catalyst is selected from the group consisting of a cerium oxide-copper catalyst, and metal particles and/or metal oxide particles including B, Mg, Al, Si, Ti, Fe, Co, Ni, Cu, Zn, Ge, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Sn, Ce, Hf, Ta, W, Re, Os, Ir, Pt, Au and mixtures thereof. 
     
     
       8. The cigarette filter of  claim 1 , wherein (i) the catalyst comprises agglomerates of catalyst particles, or (ii) the catalyst is provided on a support comprising a material selected from the group consisting of silica gel beads, molecular sieves, magnesia, alumina, silica, titania, zirconia, iron oxide, cobalt oxide, nickel oxide, copper oxide, yttria optionally doped with zirconium, manganese oxide optionally doped with palladium, ceria, activated carbon particles and mixtures thereof. 
     
     
       9. The cigarette filter of  claim 1 , wherein the catalyst comprises nanoscale-sized particles. 
     
     
       10. The cigarette filter of  claim 1 , wherein the carbon fiber composite has at least one open end and a porous cover closing the open end. 
     
     
       11. The cigarette filter of  claim 1 , wherein the carbon fiber composite has (i) an in-plane carbon fiber orientation and a compressive strength of from about 5 MPa to at least about 20 MPa, or (ii) an out-of-plane carbon fiber orientation and a compressive strength of from about 3 MPa to at least about 10 MPa. 
     
     
       12. The cigarette filter of  claim 1 , wherein:
 the carbon fiber composite has a longitudinal axis and comprises carbon fibers having a length of from about 50 μm to about 400 μm and a diameter of from about 10 μm to about 30 μm; 
 wherein the carbon fibers are oriented (i) along the longitudinal axis, (ii) at an angle relative to the longitudinal axis and/or (iii) circumferentially in the composite. 
 
     
     
       13. The cigarette filter of  claim 1 , wherein the carbon fiber composite has a length of from about 3 mm to about 20 mm, and an outer diameter of up to about 8 mm. 
     
     
       14. A cigarette, comprising: a cigarette filter according to  claim 1 ; and a tobacco column attached to the cigarette filter. 
     
     
       15. The cigarette of  claim 14 , which is an electrically heated cigarette or a cigarette including a combustible fuel element. 
     
     
       16. The cigarette of  claim 14 , including a flavoring-release additive downstream from the filter component in the cigarette filter, the flavoring-release additive including at least one flavoring which is adapted to be released in the cigarette when the flavoring-release additive is heated to at least a minimum temperature in the cigarette. 
     
     
       17. The cigarette of  claim 16 , wherein the catalyst is effective to catalyze at least the oxidation the CO, and sufficient heat is evolved during the oxidation of the CO to heat the flavoring-release additive to at least the minimum temperature such that the at least one flavoring is released in the cigarette. 
     
     
       18. The cigarette of  claim 14 , wherein the catalyst comprises nanoscale-sized particles. 
     
     
       19. A method of manufacturing a cigarette, comprising:
 placing a paper wrapper around a tobacco column; and attaching the cigarette filter according to  claim 1  to the tobacco column to form the cigarette. 
 
     
     
       20. A method of treating mainstream tobacco smoke, comprising heating or lighting the cigarette according to  claim 14  to form smoke and drawing the smoke through the cigarette, the catalyst catalyzing the chemical reaction of at least one gaseous constituent contained in the smoke. 
     
     
       21. The cigarette filter of  claim 10 , wherein a portion of the porous cover extends into the cavity. 
     
     
       22. The cigarette filter of  claim 1 , wherein the carbon fiber composite substantially contains heat evolved during the chemical reaction within the filter component.